Battens or no Battens?

November 7, 2011 | Filed under: Battens or No Battens, Misc, Roofing Answers, Roofing Installation

Greg from Florida recently sent me this question:

Q: I am looking to have a metal roof installed over my existing single layer shingle roof. I have had several estimates from companies but the one difference I see is that some companies want to use purlins (battens) and others do not. Are there a advantages / disadvantages to using purlins in this situation?

Here is my reply:

A: Good question. The first part of my response has to do with the suitability of the product for this application. There are a very few metal roof styles which MUST be installed over battens. There are some which can be installed over battens or solid decking and of course there are others which must be installed over solid decking.

Assuming the roofing you’re having installed can be installed over battens or solid decking, you then have the question of which to do. Frankly, folks will probably tell you that condensation control is a reason for using them. There really is very little validity to that in my 30+ years of experience. If the home has a well vented attic space, there is no reason for the metal roof to be mounted on battens.

The benefit to putting it on battens, though, is that the thermal break caused by the airspace will help some with energy efficiency. However, if your attic is vented well and you’re using a roof panel with reflective pigment, the added benefit of the cavity f is minimal.

The issues with battens are they can make the roof less walkable and they also mean you have to have extra trims to cover up the depth. This could also mean you will have to raise the gutters on the home if there are any.

I hope this helps. Please contact me whenever I might be of service.

todd Miller

has spent his entire career in the metal building products manufacturing industry. He is president of Isaiah Industries, an organization recognized as one of the world’s leading metal roofing manufacturers. Todd is currently Vice President of the MRA (Metal Roofing Association) and a Past Chair of MCA (Metal Construction Association). Through his website, he strives to raise the bar on standards and practices to provide property owners with the best possible products for successful roofing projects.

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6 responses to “Battens or no Battens?”

  1. bob says:

    Will metal roofing leak if screwed on top of roof shingles with no pearlings ?

  2. Del says:

    I told my roofer I wanted 24 gage metal
    in a beautiful copper color.
    Very reflective and 12” wide panels.
    He told me he ordered it in 16” panels
    instead. He said it was better then 12” wife. Is that true.
    I live close to Houston Texas, we get a lot of rain, and severe heat.

    • toddmiller says:

      Proper installation will trump everything else. Wider panels are less expensive than more narrow panels and they also install faster. Both can work well though there is a greater chance of oil canning usually the wider the panel is. Sometimes striations are added to the panels to try to combat that. A lot of times when considering panel width, I will think about the size of the home. Larger homes can handle the look of wider panels. Smaller homes usually look better to scale with a narrow panel.

  3. Rob says:

    Lake house in central Texas currently with hail damaged composition roof. Now getting bids. The area got a couple of hail storms and a sizable F3 last spring – so not a case of if, but more when is the next storm.
    Would like to add a radiant barrier underlayment directly on top of shingles, + 1×4 pine battens, + either 26, or 24 gauge Galvalume R-panel. House is a simple 9 facet roof @ 2900 sq.ft. Looking at product pricing 24 vs 26 gauge appears to be o.30 – 0.45 cents difference per sheet. Couple of questions: Do you recommend since I already have hail damage to get the thicker R-panel? Should the battens be installed in a tighter pattern for wind load? Roofers are talking about removing cyclone roof vents, so once metal roof is up how does original attic space vent?

    • Todd Miller says:

      Thanks Rob. When comparing apples and apples — all other factors being the same — yes, I would opt for the heavier gauge. Will it protect against everything? No, but ultimately it will be more resilient for your application. Though, frankly, if I had my choice between heavier gauge and concealed fasteners, I’d opt for concealed fasteners. As far as fastening pattern, go with what the panel manufacturer recommends for your area. As far as venting, attic venting is normally critical for energy efficiency and moisture control. I assume there are intake vents in the overhangs of your roof. Replacing the turbine vents with a ridge vent on your roof is probably acceptable, and I am guessing that is their plan. Please contact me anytime.

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